In recent years, it has been necessary that, for instance, in the medical field, radiation such as X-rays or gamma rays or excitation light such as fluorescence can be detected fast at every pixel.
As one of conventional detectors having such a function, there is known a gamma camera mounted in nuclear medicine diagnosis apparatuses. This gamma camera receives gamma rays emitted outside from an object body into which nucleus is injected, and outputs, for every emission position, detection information showing the amounts of the gamma rays. Practically the gamma camera is provided with a collimator, a group of scintillators, light guides, and photomultipliers (PMT) when being viewed in the gamma-ray oncoming direction, and on the output side of this photomultiplier, there is provided a position calculating circuit.
The group of scintillators is composed such that a plurality of columnar scintillators are arranged densely and adjacently to each other so that each of such scintillators has a front surface serving as an input surface. The photomultipliers each have a hexagonal input surface and are arranged densely.
Gamma rays incoming through one or more holes of the collimators are thus guided to enter one or more scintillators through the input surface of the scintillators. In such scintillators, scintillation light (pulsed light) is generated by being excited by the incident gamma rays. The scintillation light enters one or more photomultipliers from the output surface of one or more scintillators via light guides. The one or more photomultiplier convert light pulses to electrical signals so as to output electrical pulses, which are proportional to the amount of incoming light, to the position calculating circuit. Based on the one or more output pulses, the position calculating circuit calculates light emitting points, that is, incident positions of the gamma rays. Hence, from the position calculating circuit, information indicative of the emitting positions and the intensities (i.e., energy amounts) can be supplied to an image display and/or memories.
In recent years, while being provided with such a basic scintillation structure, various types of developed scintillators are known as shown in patent references 1 and 2.